1) Field of the Invention
The invention herein relates to lock mechanisms, specifically an improved tubular-type locking cylinder and dedicated key having both theft- and trip-resistant tumbler pin assemblies.
2) Description of the Prior Art
A conventional tubular-type locking cylinder 1a and key 2a is shown in FIG. 5 and FIG. 6. The said conventional tubular-type locking cylinder 1a is typically comprised of an outer housing 11, a main base 12a, a locking cylinder 13a, and a plurality of tumbler pin assemblies 14, while the key 2a of the said conventional tubular-type locking cylinder 1a is of one-piece construction and comprised of a toggling barrel 21 and a handle 22. The said toggling barrel 21 consists of a barrel member 210 having a plurality of arcuate unlocking notches 211 disposed along its outer rim, a locating element 214 extending outward laterally from the handle 22 member 220 at the said rim after the handle 22 is fastened to one side of the said rim, and, furthermore, an actuating element 213 facing inward. When the said key 2a is inserted into the entrance of the toggling barrel 21, the actuating element 213 and the locating element 214 on the outer side are respectively aligned with the actuating element slot 133 (see FIG. 6) at the top extremity of the locking cylinder shaft 13 of the said tubular-type locking cylinder 1a and the locating slot 112 on the key entry hole 111 of the outer housing 11 and then pushed into the said tubular-type locking cylinder 1a (as shown in FIG. 7), the plurality of arcuate unlocking notches 211 on the rim of the said toggling barrel 21 then contact the upper and lower pins 141 and 142 of the tumbler pin assemblies 14 at the lower extent of the locking cylinder 13a tumbler pin disc 131 and also moves against the upper extent of the main base 12a body 120a (as shown in FIG. 7), at which time the handle 22 of the said key 2a is grasped by two fingers and rotated clockwise or counter-clockwise such that the said key 2a unlocks the said tubular-type locking cylinder 1a. 
Generally speaking, the said conventional tubular-type locking cylinder 1a has no drawbacks during the unlocking operation. However, since the plurality of tumbler pin assemblies 14 between the tumbler pin disc 131 of the locking cylinder 13a and the body 120a of the main base 12a lack any anti-theft device, an ordinary thief can easily obtain a tube having a wall thickness of approximately 0.2 mm to 0.4 mm and an inner diameter equal to the that of the key 2a toggling barrel 21, slip a rubber sleeve tightly over the exterior wall of the said tube to fix a number of wire segments or half-length toothpicks equal in quantity to that of the said tumbler pin assemblies 14 and insert this into the said conventional tubular-type locking cylinder 1a in place of the key 2a to forcefully unlock the said conventional tubular-type locking cylinder 1a within five seconds. As such, the prior art is merely an average, low-price, and imprecise locking device that is not equipped with a means of theft prevention. Additionally, since the said conventional tubular-type locking cylinder 1a has no anti-theft device or locking cylinder 13a securing device, when utilized as a lock under vibrational conditions, vibrations readily rotate the locking cylinder 13a against the main base 12 and trip the said tumbler pin assemblies 14, causing the said conventional tubular-type locking cylinder 1a to malfunction or become damaged such that it is inoperable.
Based on many years of professional engagement in the tubular lock manufacturing industry, the applicant of the invention herein addressed the installation and utilization shortcomings of the conventional tubular-type locking cylinder 1a by conducting research and testing that culminated in the successful development of the improved tubular-type locking cylinder and dedicated key of the invention herein.
The objective of the invention herein is to provide an improved tubular-type locking cylinder and dedicated key that has theft- and trip-resistant tumbler pin assemblies, the detailed description of which is presented after the brief description of the drawings below.